Effect of Vanadium Content on Microstructure, Tribological and Electrochemical Properties of Carbides in Cr-Mo Steel

Despite the development of the new, modern non-metallic materials, the steel materials are largely used in various branches of industry, while in some applications they are still irreplaceable. It is expected that such a trend will remain for certain number of years. This is why the necessity is present for development of the new types of steels, which would possess even better properties. The Chromium-Molybdenum (Cr-Mo) steels, with high vanadium content, belong to the group of newer steels characterized by high values of hardness and toughness. In this research, the tests were performed on samples made from the X180CrMo12-1 steel with varying percentage of vanadium within the limits of 0.5-3%. Vanadium, as a carbide-forming alloying element, creates a carbide network of the M7C3 type around the metal matrix, and finely dispersed carbides of the V6C5 type within the metal matrix. This research was focused on determining the carbides’ composition, observing the shape of metal grains and carbide network, testing the material’s resistance to friction and wear, including the electrochemical characterization, as well. The objective was to determine the carbides microstructure and morphology, as well as to evaluate their impact on the material's characteristics. The experimental investigation was performed using the scanning electron microscopy with energy dispersive spectrometry (SEM-EDS) and X-ray diffractometric analysis (XRD). Examination of the carbide composition confirmed that it was the M7C3 carbide.